There are conventionally toy guns so configured that pressure arising from compressed gas is applied to a bullet to fire it off by a user pulling the trigger. (An example is the automatic toy gun described in Japanese Unexamined Patent Publication No. Hei 10 (1998)-197200.) This type of toy gun is used by toy gun enthusiasts for fun in target shooting (plinking) or the like at home.
The automatic toy gun described in Japanese Unexamined Patent Publication No. Hei 10 (1998)-197200 is of open bolt type. Brief description will be given to the action of a forward/backward action bolt 11 observed when bullets are fired off from this automatic toy gun. When the trigger 1 is pulled with the forward/backward action bolt 11 in a standby position close to the rear end of the gun, the following takes place: a recoil spring 27 pushes the forward/backward action bolt 11 and a hammer 21 integrally provided on the forward/backward action bolt 11 hits a opening/closing valve member 51. As the result of hitting by the hammer 21, a bullet BB receives gas pressure and is accelerated in the direction toward the front end of a gunbarrel 2 and fired off from the gun. Substantially immediately after the bullet BB is fired off from the gunbarrel 2, the forward/backward action bolt 11 starts to move back in turn due to gas pressure from an accumulator 50 and the biasing force of a rebound spring 29.
Many toy gun users request of a toy gun that it not only fires off bullets but also provides functions and the sense of use similar to those of real guns. In a toy gun so configured that a valve is opened and closed in conjunction with the movement of a bolt in the back and forth direction of a gunbarrel and a bullet is thereby loaded and fired off, the following is implemented: high impact is produced by the movement of the bolt and this makes it possible to obtain the sense of use close to that of a real gun. For this reason, toy guns so configured that a bolt is moved and bullets are thereby fired off are more popular than toy guns with a fixed bolt.
The toy gun described in Japanese Unexamined Patent Publication No. Hei 10 (1998)-197200 is so configured that the following is implemented: a bolt moves forward and hits a valve and thereby opens the valve to fire off a bullet; and after the bolt thereafter moves back, the valve is closed. As mentioned above, this toy gun provides the sense of use close to that of a real gun. In case of this toy gun, however, the hammer, the valve, and bullets are not positioned in alignment. If the hammer, the valve, and bullets exist in alignment, it must be possible to further reduce the size of a bullet firing mechanism and more efficiently apply gas pressure to bullets. Aside from the automatic toy gun described in Japanese Unexamined Patent Publication No. Hei 10 (1998)-197200, an open bolt-type toy gun in which a hammer, a valve, and bullets exist substantially in alignment is possible. This will be designated as toy gun in virtual case.
This toy gun in virtual case is equipped with a movable bolt. This bolt has at its rear part a space (variable volume pressure chamber) into which air or gas flows. This variable volume pressure chamber is a space into which gas flows after a bullet is fired off. Gas that flowed into this variable volume pressure chamber pushes the bolt backward by its pressure. As long as the variable volume pressure chamber is filled with gas, the gas continuously pushes the bolt backward. That is, the above bolt moves backward after a bullet is fired off. This bolt breaks away from a valve body immediately before it arrives at the backmost retreat position. This removes the airtightness in the bolt and the gas in the variable volume pressure chamber is discharged to the atmosphere. As a result, the pressure of the gas in the variable volume pressure chamber is reduced.
For this reason, the following takes place in the toy gun in virtual case: the time for which the bolt continuously receives pressure from gas is lengthened as the closed-end cylindrical portion forming the variable volume pressure chamber becomes longer. As a result, the recoil shock given to the user by the toy gun in virtual case is also increased.
However, lengthening the closed-end cylindrical portion poses another problem. As the closed-end cylindrical portion becomes longer, the distance the bolt travels until it hits the hammer after it is fit into the closed-end cylindrical portion is lengthened. As a result, the air in the closed-end cylindrical portion functions as if it were a buffer material (air cushion) and this reduces the impact by which the bolt hits the hammer. If the recoil spring is strengthened to increase the impact by which the hammer is hit to solve the above problem, a new problem would arise. The recoil shock produced when the bolt is moved backward by gas pressure is reduced.